[PATCH v2] hfsplus: avoid crash on failed block map free

[Vyacheslav Dubeyko <slava@dubeyko.com>]

Hi Alan,

Do you agree with second version of the patch?

With the best regards,
Vyacheslav Dubeyko.
--
From: Alan Cox <alan@linux.intel.com>
Subject: [PATCH v2] hfsplus: avoid crash on failed block map free

v1->v2
* Change hardcoded error code on -ENOENT.
* Add return -EIO for the case of kmap error.
* Fix issue with twice mutex unlock.
* Fix issue with printing kmap error message on every call.

If the read fails we kmap an error code. This doesn't end well. Instead print a critical error and pray. This mirrors the rest of the fs behaviour with critical error cases.

Acked-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
---
 fs/hfsplus/bitmap.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/fs/hfsplus/bitmap.c b/fs/hfsplus/bitmap.c
index 4cfbe2e..6feefc0 100644
--- a/fs/hfsplus/bitmap.c
+++ b/fs/hfsplus/bitmap.c
@@ -176,12 +176,14 @@ int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
 	dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
 	/* are all of the bits in range? */
 	if ((offset + count) > sbi->total_blocks)
-		return -2;
+		return -ENOENT;
 
 	mutex_lock(&sbi->alloc_mutex);
 	mapping = sbi->alloc_file->i_mapping;
 	pnr = offset / PAGE_CACHE_BITS;
 	page = read_mapping_page(mapping, pnr, NULL);
+	if (IS_ERR(page))
+		goto kaboom;
 	pptr = kmap(page);
 	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
 	end = pptr + PAGE_CACHE_BITS / 32;
@@ -214,6 +216,8 @@ int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
 		set_page_dirty(page);
 		kunmap(page);
 		page = read_mapping_page(mapping, ++pnr, NULL);
+		if (IS_ERR(page))
+			goto kaboom;
 		pptr = kmap(page);
 		curr = pptr;
 		end = pptr + PAGE_CACHE_BITS / 32;
@@ -232,4 +236,11 @@ out:
 	mutex_unlock(&sbi->alloc_mutex);
 
 	return 0;
+
+kaboom:
+	printk(KERN_CRIT "hfsplus: unable to mark blocks free: error %ld\n",
+			PTR_ERR(page));
+	mutex_unlock(&sbi->alloc_mutex);
+
+	return -EIO;
 }
-- 
1.7.9.5